These Men Ate 6,000 Calories a Day for Science

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A group of healthy guys recently took on a task some people
would envy: They consumed 6,000 calories a day, for science.
Now, as a result of this study, scientists say they have a better
idea of why people who are obese also tend to develop diabetes.

In the study, six middle-age men who were either normal weight or
only slightly overweight volunteered to start eating double what
they typically consumed in a day, so they would rapidly
gain weight. The men were also confined to hospital beds so
they would not get physical activity.

After a week of eating 6,200 calories a day — with a diet rich in
carbohydrates and fat that included foods like hamburgers, pizza
and cookies — the men gained nearly 8 lbs. (3.5 kilograms), on
average. All of this added weight was fat. [ 7
Biggest Diet Myths ]

The researchers were interested in learning how obesity triggers
insulin resistance, a condition in which the body's cells
stop responding to the hormone insulin. Because insulin helps
blood sugar get inside cells, insulin resistance leads to a
buildup of sugar in the bloodstream, and can cause type 2
diabetes.

Scientists have a number of theories for why obesity leads to
insulin resistance, including that obesity increases fatty acids
in the blood, or promotes inflammation. But these changes may
happen only after a person has been obese for a long time.

The new study allowed researchers to see what happens when a
person is in the very early
stages of obesity, and to pinpoint the first step in insulin
resistance.

In the study, the men developed insulin resistance after just two
to three days, the researchers said.

Samples of the participants' urine and fat tissue showed that
there was an increase in oxidative stress in their bodies, which
means there was an increase in compounds that are toxic to cells.
This oxidative stress caused changes in a protein called GLUT4,
which normally helps sugar get inside cells.

The GLUT4 changes may have impaired the ability of this protein
to respond to the hormone insulin, thus leading to insulin
resistance, the researchers said.

"We may have found the initial events that are responsible for
the insulin resistance," said study researcher Salim Merali, a
professor of pharmaceutical sciences at Temple University in
Philadelphia.

The new findings suggest that treatments that use
antioxidants might help prevent insulin resistance, Merali
said.

However, future studies are needed to confirm this hypothesis and
to see whether oxidative stress causes other changes that
contribute to insulin resistance, the researchers said.

The study is published today (Sept. 9) in the journal Science
Translational Medicine.